Display devices



W. J. DOWNS DISPLAY DEVICES July 5, 1960 4 Sheets-Sheet 1 Filed Dec. 20, 1957 INVENTOR WILLIAM J. DOWNS ATTORNEY y 1960 w. J. DOWNS 2,943,408

DISPLAY DEVICES Filed Dec. 20, 1957 4 Sheets-Sheet 2 INVENTOR WILL/AM J DOWNS BY M+W ATTORNEY W. J. DOWNS DISPLAY DEVICES July 5, 1960 4 Sheets-Sheet 3 Filed Dec. 20. 1957 INVENTOR WILL/AM J DOWNS ATTORNEY July 5, 1960 w. J. DOWNS 2,943,408

DISPLAY DEVICES Filed Dec. 20, 1957 4 Sheets-Sheet 4 I- m g; m #1: an I:

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ATTORNEY DISPLAY DEVICES William J. Downs, Cincinnati, Ohio, assignor of one-half to John J. Kebba, Queens Village, and one-half to John A. Pater'acki, In, Rye, NY.

Filed Dec. 20, 1957, Ser. No. 704,046

3 Claims. (Cl. ill-32) The present invention relates to display devices, and more particularly to display devices adapted to present to view a plurality of display panels in serial fashion in an endless repeating cycle.

An object of the present invention is to provide display devices in which there is presented to View an apparently endless procession of display panels.

Another object of the invention is the provision of display devices having a plurality of panels movable on tracks so arranged as to assure a smooth movement to the panels and to avoid binding or shuddering of the panels during passage along the, tracks.

-A further object of the present invention is the provision of display devices comprising a plurality of movable panels having guide means connected thereto which will enable movement of the panels with a minimum of effort.

A still further object of the present invention is the provision of display devices having a plurality of movable panels drivably interconnected along only a single line in such a manner as to avoid misalignment and jamming of the panels.

Yet another object of the present invention is the provision of a display device having a plurality of panels movable about a closed path having a display run and a return run with provision of means for smoothly and rapidly transferring the panels from one run to the other.

Still another object is to provide a display device of the foregoing character in which the panels are transferred from one run to the other While at all times maintaining the same face of the panel presented to the same side of the display device.

Finally, it is an object of the present invention to provide display devices which will be relatively inexpensive to manufacture, easy to install, maintain, operate and repair, and rugged and durable in use.

Other objects and features of the present invention will become apparent from a consideration of the following description, taken in conjunction with the accompanying drawings, in which:

Figures 1A and 1B together comprise a plan view of a display device according to the present invention;

Figure 2 is a transverse cross-sectional view taken on the line 22 of Figure 1A;

"Figures 3A and 3B together are a cross-sectional view of 'a display device according to the present invention taken on the line 3--3 of Figure 2;

Figure 4 is a side elevational view of the left end of a display device according to the present invention as viewed from the front, with parts broken away for clarity;

Figure 5 is a fragmentary side cross-sectional View taken on the line 5-5 of Figure 3B;

Figure 6 is a transverse fragmentary cross-sectional view taken on the line 66 of Figure 4 with parts omitted for clarity;

Figure 7 is a transverse fragmentary cross-sectional view taken on the line 7-7 of Figure 4 with parts omitted for clarity;

Patented July 5, 1960 "Figure 8 is a transverse fragmentary cross-sectional view taken on the line 8-8 of Figure 4 with parts omitted for clarity; and

Figure 9 is a transverse fragmentary cross-sectional view taken on the line 99 of Figure 4 with parts omitted for clarity.

Referring now to the drawings in greater detail, there is shown a display device according to the present invention indicated generally at 1 and comprising a rigid openwork frame 3 including a base made up of a pair of spaced parallel horizontal channel beams 5 disposed longitudinally of the device and a plurality of longitudinally spaced transverse channel beams 6 rigidly interconnecting beams 5. Upstanding from the rear side edge of the base is a plurality of longitudinally spaced vertical channel beams 7 and extending forwardly from the upper ends of beams '7 in cantilever relationship is a plurality of horizontal transverse channel beams 9.

Extending interconnectingly between and secured to the upper side of beams 5 adjacent either end thereof is a pair of coplanar horizontal plates 11 and 13. Plate 11 carries a journal mounting for a sprocket wheel 15 which is disposed in a horizontal plane and is rotated about a vertical axis through gear reduction unit 17 by an electric motor 19 having suitable connection to a source ofelectric power (not shown). Plate 13 carries a sprocket wheel 21 which is disposed in the same horizontal plane as Wheel 15 and rotates about a vertical axis parallel to the axis of wheel 15. It should be noted that Wheels 15 and 21 are parallel to and spaced equal distances above plates 11 and 13. Reeved about wheels 15 and 21 is an endless flexible drive member comprising a chain 23 disposed in a horizontal plane and having a straight, forward run 25 and a straight rear run 27 parallel to run 25. Chain 23 is of the conventional double sidebar and pintle type, the sidebars being horizontal and the pintles vertical.

Secured within the lower portions of frame 3 is a pair of lower tracks 29 and 31 parallel to each other and to beams 5. The track 29 is located in a horizontal plane below the plane of the track 31 and the tracks have a substantial extent of overlap while being longitudinally offset from each other a substantial distance at both ends in the same direction for a purpose that will appear more fully below. Tracks 29 and 31 have forward runs 33 and 35, respectively, and rear runs 37 and 39, respectively. The front and rear runs of each track are essentially mirror images of each other and except as otherwise noted the description of one will suffice for the other. As shown more particularly in Figures 2 and 6, either run of track 29 comprises a channel 41 including a lower horizontal web 43 and a pair of vertical side flanges 45 extending upwardly from the edges of the web 43.

Either run of track 31 is comprised of a channel 47 including a pair of spaced, vertical, parallel flanges 49 and a pair of opposed inwardly directed horizontal flanges 51 which lie in a common horizontal plane and are parallel to each other and are spaced apart by a longitudinal gap 52. Tracks 29 and 31 are of the same width and are precisely vertically superposed over most of their longitudinal extent; and hence, the greatest portion of the length of flanges 49 will comprise merely upward extensions of flanges 45 of channel 41, as seen for example in Figure 7, the flanges 51 in that case comprising the bottom of track 31. At the portion of track 31 which does not overlap track 29, seen as the right-hand portion of track 31 in Figure 3B, flanges 51 cannot serve as the bottom of track 31, so that as one looks to the right along Figure 3B, the flanges 51 are seen to merge with an imperforate web 53 which forms the bottom of track 31 in the overhanging portion of track 31 beyond wheel 21.

A pair of upper tracks 55 and 57 are also provided which are secured within the upper portion of frame 3 and also extend parallel to beams 5. Tracks 55 and 57 have straight, forward runs 59 and 61, respectively, and, parallel to these forward runs, straight, rear runs 63 and 65 respectively. Tracks 55 and 57 are directly superposed above in vertical alignment and congruent with lower tracks 29 and 31 respectively. As also in the case of tracks 29 and 31, the forward and rear runs of each of tracks 55 and 57 are mirror images of'each other so that a description of one will sufiice for both. As shown in Figure 8, either run of track 55 comprises a pair of channels 67 having parallel spaced vertical legs 69 terminating upwardly in parallel coplanar horizontal legs 71 extending toward each other but spaced apart by an elongated longitudinal gap 73. At its end above wheel 15, track 55 has an arcuate portion 75; and at its end above Wheel 21, track 55 has an arcuate portion 77. A-rcuate portions 75 and 77 are coaxial with wheels 15 and 21 respectively.

Track 57 comprises a pair of channels 79 having vertical parallel webs 8d spaced apart a distance equal to the width of gap 73 and terminating at their lower edges in oppositely outwardly directed lower flanges 83 and at their upper edges in oppositely outwardly directed upper flanges 85. Upper flanges 85 are secured to the lower surfaces of the transverse beams 9 and lower flanges 83 are secured to the upper surfaces of legs 71 in the region of overlap of tracks 55 and 57.

Mounted for serial movement in the various tracks is a plurality of vertically disposed display panels 87 each comprising a rigid'rectangular frame 89. As shown in Figure 6, the frame is formed of channel members presenting a slot 90 extending along the inner edge of each side thereof for the detachable reception of a display card 91 which may bear on its forward side an advertising message or other visual representation. The channel members forming the frames are broken away on their forward sides at 93 for the easy insertion and removal of cards 91 into and out of the slots 90. This feature is illustrated in Figure 4.

Extending to the rear from each corner of frame 89 is a rigid arm 95. Guide means 97 and 99 are carried by the arms 95 extending from the lower corners of the frame 89 and guide means 101 and 103 are carried by the arms 95 extending from the upper corners of the frame. As shown in Figure 6, guide means 97 is mounted for movement in track 29 and comprises a vertical shaft 105 which may be detachably secured at its upper end to an arm 95 and which extends-downwardly through gap 52 and terminates at its lower end in a yoke 107 in which a roller 109 is journalled for rotation about a horizontal axis. Roller 109 rolls on the upper surface of web 43. Intermediate the ends of shaft 105 in a region of the flanges 45 and journalled on the shaft 105 for rotation about a vertical axis is a roller 111 of a relatively large diameter only slightly less than the distance between flanges 45 and adapted to guidingly roll upon either of the confronting side faces of flanges 45. Roller 111 also maintains guide means 97 against vertical dislodgment from track 29. Chain 23 is journalled on shaft 105 between roller 111 and yoke 107, shaft 105 replacing one of the pintles of chain 23 so as to provide a point of swingable interconnection between chain 23 and shaft 105.

Guide means 99, as illustrated in Figure 7, is mounted for movement in channel 31 and comprises a vertical shaft 113 substantially shorter than shaft 105 and which also may be detachably secured at its upper end to an arm 95. The shaft 113 terminates at its lower end in a yoke 115 in which is journalled for rotation about a horizontal axis a roller 117 which rolls on flanges 51 and webs 53. A short distance above yoke 115, a relatively large diameter roller 119 is journalled on shaft 113 for rotation about a vertical axis, the roller 119 is of a diameter only slightly less than the distance between flanges 49 so as to lend lateral stability to guide means 99 by rolling contact with either of the opposed inner side faces of flanges 49.

With reference more particularly to Figure 8, guide means 101 carried by an arm at one upper corner of the frame 89 is mounted for movement in the channel '55 and guide means 103 carried by an arm 95 at the other upper corner of the frame is mounted for movement in the channel 57. The guide means 101 includes a relatively short upwardly extending shaft 121 which may be adjustably secured to an arm 95 and at the upper end of which is rotatably mounted a relatively large diameter roller 1123 disposed in upper track 55. Roller 123 is of a diameter only slightly less than the distance between vertical legs 69 of channels 67 so as rollably to contact either of the opposed inner side faces of legs 69 to lend lateral stability to guide means 101. Guide means 103, as shown in Figure 9, comprises a relatively long upwardly extending shaft 125 which may be detachably secured at its lower end to an arm 95 and at the upper end of which is journalled for rotation about a vertical axis a relatively small diameter roller 127 disposed in track 57. Roller 127 is of a diameter only slightly less than the distance between vertical webs 81 of channels 79 so as rollably to contact either of the opposed inner side faces of webs 81 thereby to lend lateral stability to guide means 103.

Shafts and 121 are in axial alignment, as are also shafts 113 and 125. Subjacent support is lent to panels 87 only by guide means 97 and 99 which also provide lateral support. Guide means 101 and 103 serve only to afford lateral aligning support for the upper ends of panels 87. Panels 87 have only a single point of driving interconnection with drive chain 23, and this single point is immediately adjacent roller 109 of the associated guide means 97. By this arrangement, the single point of driving impulse is applied to panels 87 as low as possible, even lower than the spaced point of subjacent support afforded by roller 117, so that the stability of the panels is greatly improved.

Thus far, structure has been described by which the panels may be moved through a path of rectilinear motion along the straight runs of the tracks. In order to provide a continuous cycle of movement, however, it is necessary to transfer the panels alternately between track runs. At the same time, in order to maintain the display device as compact as possible so as to have the least depth, it is highly desirable that the panels do not undergo substantial bodily turning movement when passing from one run to another but that they move along the runs with the same face of the panel presented to the same side of the display device at all times. Obviously, in order to achieve this movement, the leading vertical edge of a panel in one run becomes the trailing vertical edge in the other run, and vice versa. Accordingly, a further important feature of the invention comprises the transfer means for achieving this performang Inasmuch as each panel has four points of contact with the tracks, represented by its four guide means, provision must be made for transferring each of these four guide means from one run to another and at the same time preserving the panel orientation described above.

The structure for the transfer of guide means 97 is relatively simple. As best seen in Figures 2 and 6, webs 43 of the track 29 are coplanar with and terminate at the edges of plates 11 and '13, so that rollers 109 simply ride on these Webs during passage along the straight portions of the track runsand then move smoothly onto plates 11 or 13 while passing about wheels 15 or 21, respectively. Thus, plates 11 and 13 comprise the trans fer means for guide means 97 and are therefore a portion of track 29. Correspondingly, arcuate portions 75 and 77 of track 55 comprise the transfer means for guide means 101. The transfer of guide means 97 is a rela:

tivelyjeasy matter because guide means 97 is carriedabout wheels 15 and 21 by chain 23; and the transfer of guide means 101 is also relatively easy because guide means 101 isvertically aligned with guide means 97.

However, the transfer of guide means 99 and"103 would ordinarily present a considerable problem inasmuch as these guide means are located at what is the free end of the panel relative to chain 23. Accordingly, transfer sections 129 and 131 are provided for guide means 99 at opposite ends of and comprising a portion of track 31 and transfer sections 133 and 135 are provided for guide means 103 at opposite ends of and comprising a portion of track 57.

Transfer section 129 is Y-shaped and comprises an entrant portion 137 and an exit portion 139 with a reversing leg 141 at the junction of portions 137 and 139. Section 129 is in effect a continuation of track 31 at its left end as seen in Figure 3A and comprises webs 143 which form in effect horizontal continuations of flanges 51 and vertical upstanding flanges 145 at both sides of the webs 143 which form in effect continuations of (flanges 49. In order to assure that guide means 99 will not re-enter portion 137 after reversal in leg 141, but will leave through portion 139, a gate 147 is pivoted at the junction of the inner flanges 145 of portions 137 and 139 and extends across portion 137 to contact the junction of the outer flanges of portion 137 and leg 141. A leaf spring 149 yieldably retains gate 147 in this position but permits guide means 99 to push gate 147 open against the action of spring 1 49 thereby to permit passage of guide means 99 from portion 137 to leg 141. Thereafter, gate 147 returns to the closed position shown in Figure 3A and guides guide means 99 from leg 141 into exit portion 139.

In order to permit guide means 97 to continue toward wheel 15 along that portion of forward run 33 of track 29 which is not overlapped by track 31, but at the same time to assure the entry of guide means 99 into entrant portion 137, the outer flange 145 of portion 137 is broken away in a gap 151. Gap 151 is vertically aligned with and of the same lateral width as gap 52 of track 29, andthis relatively small lateral width is sufiicient to pass shaft 105 of guide means 97 but insufficient to pass roller 119 of guide means 99. Therefore, shaft 105 passes straight through gap 151 but roller 119 and with it guide means 99 veers 011 into entrant portion 137. A similar gap 151 having the same purpose and function is located in. the outer flanges 145 of portion 139 in vertical alignment with the gap 52 of the rear run 37 of track 29.

It would be expected that guide means 97 and 99, and more particularly their lowermost points of supporting contact, would be spaced apart a distance equal to the distance between the beginning of entrant portion 137 and the point of tangency of wheel 15 with forward run 33 of track 29, which would also be to say a distance equal to the distance between the end of exit portion 139 and the point of tangency of wheel 15 with rear run 37 of track 29. However, a very important feature of the present invention resides in the fact that this is not so. As a matter of fact, the beginning of entrant portion 137 and the end of exit portion 139 are spaced from the points of tangency of wheel 15 with the runs of track 29 a common distance which is greater than the distance between guide means 97 and 99. Thus, guide means 99 first enters portion 137 while guide means 97 is still on its rectilinear path along forward run 33; and guide means 99 leavesexit portion 139 after guide means 97 has passed a distance along its rectilinear path along rear run 37. When guide means 97 is at the points of tangency of wheel 15, guide means 99 has either almost reached gate 147 in entrant portion 137 or has just passed gate 147 in exit portion 139. The purpose of this arrangement is to assure smooth reversal of guide means 99 in reversing leg 141 without interference with the closing of gate'147. Thus, a conventional portion of the longi- 5 tudinal component of movement of guide means 97 while passing about wheel 15 is represented by corresponding rectilinear movement of guide means 99 in first one and then the other direction in reversing leg 141.

Transfer section 131 is essentially a mirror image, of transfer section 129 and need not be described in detail, similar reference characters being employed to designate corresponding elements. It is very important to note, however, that section 131 does not have the same spaced relationship with regard to wheel 21 as section 129 has with regard to Wheel 15. In the case of section 131, the entrant portion begins and the exit portion ends a distance from the points of tangency of wheel 21 which is less than the distance between guide means 97 and 99, the

very reverse of section 129, so that guide means 99 enters section 131 before guide means 97, has reached wheel 21 and leaves section 131 after guide means 97 has left wheel 21, the same as in section 129. In other words, transfer sections 129 and 131 have reversed spaced relationships with regard to their respective chain wheels in order to preserve the same structural and functional relationships with regard to the guide means of panels 87. Thus, although chain 23 and track 29 are congruent and hence have straight runs of identical length, the straight runs of track 31 are substantially shorter than those of chain 23 or track 29. Nevertheless, the junction of the entrance and exit portions of section 129 is spaced from the axis of wheel 15 a distance which is the same as the distance between the junction of the entrance and exit portions of section 131 and the axis of wheel 21.

Apart from this overall distinction, the features as to which section 131 differs from section 129 are two: in the first place, gate 147 of section 131 is reversed in position relative to gate 147 of section 129 inasmuch as the positions of the entrant and exit portions are reversed; and in the second place, since the right end of track 29 underlaps track 31 as seen in Figure 3B, the inner confronting flanges 49 of track 31 are broken away in gaps 155 and gap 52 swings inwardly about wheel 21 so that flanges 51 merge with imperforate web 53, all for the purpose of permitting movement of guide means 97 about wheel 21. It must be noted, however, that the longitudinal extent of gaps 155 is less than the diameter of rollers 119 of guide means 99, so that guide means 97 will pass about wheel 21 but guide means 99 continues straight on past wheel 21 toward transfer section 131.

The transfer sections 133 and 135 of upper track 57 are analogous in structure and function to those of sections 129 and 131 respectively and hence need be only briefly described. Section 133, which has substantially the same cross-sectional configuration as the straight runs of track 57, accommodates guide means 103 and has an entrant portion 157 and an exit portion 159 joining in a reversing leg 161, one-way passage through portion 157' into leg 161 and out through portion 157 being assured by a spring-urged gate 163 similar to gate 147. To permit entry of guide means 103 into section 133 the innermost opposed channels 67 are broken away in confronting gaps 165 of a longitudinal extent sufficient to permit passage of shaft of guide means 103 therethrough but insuflicient to permit passage of roller 123 of guide means 101 therethrough, thereby allowing guide means 103 to enter and leave section 133 but preventing guide means 101 from leaving track 55.

As in the case of transfer sections 129 and 131, so also transfer section is the mirror image of section 133, except that the gate 167 thereof is reversed and the channels 67 are broken away in confronting gaps 169" for a purpose and with a function analogous to those tracks 29, 31, 55 and 57 are all parallel to each other and horizontal. Moreover, the distance between the runs of each track is constant for all tracks and the means of this constant distance is. the distance between. the runs,

of track 23. Therefore, the movement of the panels when the associated guide means are in contact with the straight track runs-will be rectilinear with no tipping or swaying so that the appearance of the moving panels when viewed from the front will be attractive.- :In order to preserve this attractive appearance and to mask the transfer movementof the panels at the ends of the-dis.- play device, fixed vertical panels 171 are secured to .each end of the front of frame 3. Panels 171 extend toward the middle of the display device a short distance beyond the beginning of entrant portions 137 and 157 of trans fer sections 129 and 133, respectively, and beyondwheel 21 so that transfer movement of the panels is invisible when viewed from the front.

The operation of the display device according to the present invention is as follows:

When motor 19 is actuated, wheel is drivenin a clockwise direction as seen in Figure 3A, thus in turn circulating drive chain 23. Through the agency of guide means 97 to which chain Q3 is swingably secured, panels 89 are pulled along forward run 33 of track 29 to the left as seen in Figures 1A and 1B,'the rollers 109 rolling on webs 43 and'the rollers 1'17 rolling on flanges 51 until rollers 109 leave'web 43 and roll onto plate 11. At about this time, guide means 99 enter portion 137, the diameter of roller 119 assuring that guide means 99 will not pass through gap 151. Shortly thereafter, guide means 97 reach the point of tangency of wheel 15 with forward run 33 of track 29, and by this time guide means 99 is well into entrant portion 137. Well before guide means 97 reach their leftmost position as seen in Figure 3A, guide means 99 push open gate 147 and enter into reversing leg 141. The movements of guide'means 99 in leg 141 are initially a short distance to the left followed by a short period of relatively little movement, and finally to the right again in a reverse direction. Gate 147, which hassprung closed behind guide means 99, now shunts the guide means into exit portion 139 after guide means 97 have had a substantial component of motion to the right about wheel 15.

As this reverse motion begins, panels 87, which had heretofore been pulled along by their leading lower corner by chain 23, are now pushed along from the rear by that same corner; and the previously leading edges ofthe panels become the rearedges, and vice versa. This reverse motion proceeds in exactly the opposite sense as that previously described, while the panels traverse the return run in the opposite direction.

Meanwhile, guide means 101 and 103 at the top of the panel have been following the same path of motion as guide means 97 and 99 respectively. While a guide means 97 has been passing about wheel 15, guide means- 101 of the same panel has been passing about arcuate portion 75 of track 55 in a congruent path; and the motion of guide means 99 through transfer section 129 has been duplicated by guide means 103 in transfer section 133, the gaps 165 permitting movement therethrough of the guide means 103 but preventing movement therethrough of guide means 101 along both the forward and rear runs of tracks 55 and 57.

At the right-hand end of the display device, as seen in Figures 1B and 3B, the panel is pushed along the return runs of the tracks by the return run of drive chain 23, and guide means 103 passes through gap 169 and enters transfer section 135 while guide means 99 is rolling past gap 155 along web 53 and entering transfer section 131, gap 155 being too short to permit exit of roller 119 through that opening. Thereafter, guide means 101 reaches the-point of tangencyof wheel 21 with-the rear straight runof track 55 but cannot pass through gap 169 and therefore starts about arcuate portion 77 at the same time that guide means 97 passes through gap and starts about wheel 21. Movement toward the forward run is thereafter the reverse of that just described; and apart from the differences pointed out immediately above, the cycle of movement in the transfer region at this end of the display device is the same as that at the other end of the display device.

In view of the foregoing, it will be obvious that all of the initially recited objects of the present invention have been achieved.

Although the present invention has been described in connection with preferred embodiments, it is to be understood that modifications and variations may be resorted to without departing from the scope of the invention, as those skilled in this art will readily understand. Such modifications and variations are considered to be within the purview of the present invention as defined by the appended claims.

What is claimed is:

1. A display device comprising an endless flexible drive member having a pair of parallel runs disposed in a common horizontal plane, means for circulating the drive member, a plurality of vertically disposed display panels each having a point of swingable interconnection with the drive member, four horizontal tracks disposed one above the other and each defining an elongated closed path having a pair of runs parallel to each other and to the ms of the drive member and interconnected at their ends by transfer track sections, the first and second of said four tracks being disposed above the display panels and the third and fourth of said four tracks being disposed below the display panels, the first track being the uppermost of the four and the fourth track being-the lowermost of the four, the first and second tracks being longitudinally offset from each other and the third and fourth tracks being longitudinally offset from each other, the first and third tracks being in vertical alignment and the second and fourth tracks being in vertical alignment, the first and third tracks extending beyond the second and fourth tracks at one end of the device, and the second and fourth tracks extending beyond the first and third tracks at the other end of the device, four spaced guide means mounted on each panel, the first and second of the four guide means being mounted on and spaced apart longitudinally of an upper portion of the panel and individually movably contacting the first and second tracks, respectively, the third and fourth of the four guide means being mounted on and spaced apart longitudinally of a lower portion of the panel and individually movably contacting the third and fourth tracks, respectively, to guide portions of the panels in closed paths defined by the tracks, the second track having openings through its end adjacent said one end of the device and through its sides adjacent the transfer section of the first track adjacent said other end of the device to permit the first guide means to pass through the second track and continue along the first track, the third track having openings through its end adjacent said other end of the device and through its sides adjacent the transfer section of the fourth track adjacent said one end of the device to permit the fourth guide means to pass through the third track and continue along the fourth track, the second and third guide means having portions too large to pass through the said openingsthrough second and third' sprocket wheel at each end of the fourth track and of substantially the same diameter as the distance between the runs of'thefourth track, the endless drive member extendingbetween and about the sprocket wheels, the transfer sections at the ends of the secondtrack being circular,.

References Cited in the file of this patent UNITED STATES PATENTS 844,344 Fletcher Feb. 19, 1907 10 Bell Aug. 2, 1932 Mutschler et al Sept. 27, 1932 Littman Nov. 8, 1932 Pfiueger Mar. 27, 1951 Bustamante Aug. 25, 1953 Bustamante May 28, 1959 

